Brake systems in vehicles generally include primary and secondary brake systems, which include, respectively, the service brakes and the parking brakes. The service brake system is generally used for stopping a vehicle during normal operations by applying a decelerating tangential force to at least the driven wheels of the vehicle. The service brake system is generally activated by the operator, most commonly via a brake pedal. The decelerating force is most often applied by a friction element, such as a brake shoe bearing on the friction lining of a drum, or by brake pads bearing on a disk. The parking, or auxiliary, brake system, on the other hand, is most often applied when a vehicle is parked for a relatively long period. That system typically takes the form of a clamping device, such as a clamp applied to the drive shaft of the vehicle, and a hand-operated lever or a foot pedal usually achieves activation.
During a temporary halt, such as waiting for a traffic signal to turn green, the service brake system is generally employed. In such situations, the driver may unthinkingly depress the service brakes (brake pedal) with significantly higher force than is required to keep the vehicle stationary. Generally, a driver will apply force to the brake pedal until the effort of that action becomes uncomfortable. Because the friction application device (e.g., the brake pad) is directly responsive to the activation device (e.g., the brake pedal), this action causes high compression of the brake pads, preventing their full retraction when the brake pedal is released. That effect leads to increased brake drag during operation, which in turn affects fuel efficiency, vehicular emissions, and general wear and tear to the vehicle.
In addition, excess braking pressure can lead to residual brake drag. When the driver applies a high level of braking force, brake system pressure does not immediately go to zero when the operator releases the pedal. Because of that pressure, the brake pads or shoes maintain contact with the disk or drum during the time required for the pressure to fall off. It can readily be seen that this effect produces a number of negative results, including excess fuel consumption and emissions required to overcome that drag, and excess brake wear produced by that drag.
No solution currently exists to counter brake drag owing to excessive brake force being applied during short vehicle halts.